Solvent refining of mineral oil



Patented Jan. 31, 1939 J UNITED STATES PATENT OFFICE SOLVENT REFINING'OF MINERAL on. Louis A. Clarke, and Edwin, c. Knowles;

. Beacon, N. Y., assignors to The Texas Company, New York, N. Y., a corporation of Dela- I ware I No Drawing.

8 Claims.

constituents of the oil of differing viscosity indices. I More specifically, the invention contemplates extracting mineral lubricating -oil with ortho chlorphenol in the presence of a modifying sol- .l'5 vent, compound, such as ethylene chlorhydrin,

and also ethylene chlorhydrin saturated with hydrogen chloride. Extraction with the chlorphenol and. modifying solvent mixture may be carried out in the presence of a diluent solvent such as a light petroleum fraction of the character of propane. .Incarrying out the extraction, the oil is brought into'contact with the solvent mixture under 7 2 conditions of temperature best adapted to effect i theparticular degree of separation desired. Af-

'ter effecting intimate contact between solvent and oil, the mixture is allowed to separate into extract and raflinate phases. The extract phase contains relatively low viscosity index constituents andother undesired impurities of the oil dissolved in the bulkof the solvent liquid, while I the raflinate phase comprises the relatively high viscosity index constituents of the oil mixed with some of the solvent. ,These phases are separated from each other and the solvent liquid 'recovered therefrom.

, In our co-pending application, Serial No. 44,- 254, filed October 9, 1935, we have described'a process for solvent refining :of mineral oil with 40 para chlorphenol and have there disclosed the unexpected improvement in the solvent refining 7 action which is realized when extracting mineral oil with this latter compound.

" We have found however that ortho chlorphenol by itself is unsuitable as aseparating solvent for mineral lubricating; oil. This solvent is miscible with mineral lubricating oil at relatively low temperatures, and it also exerts a high solvent power upon both low and high viscosity index constituents of mineral oil so that'it is impossible toeifect any substantial separation of the oil into its components. This high solvent power of ortho chlorphenol is'also apparent when the solvent is used in admixture with its isomer, para rid-chlorphenol, so-that when chlorphenol mixtures Application October 9, 1935, Serial No. 44,256

seems to impart anti-solvent properties to the mixture, is of advantage in decreasing the otherwise high solvent power of the ortho isomer for the paraffinic or relatively high viscosity index constituents and permits realizing an improved 10 yield of rafiinate oil. Chloracetic acid has also been found satisfactory as a modifying solvent, although ethylene chlorhydrin is preferable since it is a neutral substance and does not tend to react with the chlorphenol during continued use. .15

Ethylene chlorhydrin is therefore particularly suitable for this purpose and also when saturated with hydrogen chloride gas it provides a solvent mixture with ortho chlorphenol which is very effective in segregating from lubricating oil 20 stocks containing solid and semi-solid asphaltic constituents, lubricating oil fractions which are relatively low in residual carbon content.

We have discovered that the addition of a small amount of highly ionizable material to an ex- 25 traction solvent increases the effectiveness of the solvent in removing solid and semi-solid asphaltic material from residual lubricating oil stocks.

While ortho chlorphenol is itself highly ioniz- 30 able, the addition of a non-acidic modifying antisolvent such as ethylene chlorhydrin, tends to decrease the extractive power of the mixture for these asphaltic constituents. Accordingly, the addition of a small amount of hydrogen chloride 35 to the solvent mixture offsets any tendency of the added solvent to reduce the extractive power of the solvent mixture for these solid and semisolid asphaltic bodies contained in the oil undergoing treatment.

The modifying antisolvent may be used in varying amounts up to as high as about 40% by volume of the chlorphenol, and when the mixture is saturated with hydrogen chloride it has relatively high solvent power for the asphaltic constituents of the oil.

Reference will now be made to the following experiments in which a heavy residual oil was extracted with a mixture of about equal parts of 50 ortho and para chlorphenol in the presence of chlorphenol mixture in the proportion of 20% by volume of the phenol mixture.

In carrying out this experiment, the oil was first diluted with pentane in the proportion of two parts of pentane to one part of the oil. The diluted oil was subjected to countercurrent contact with the modified solvent in an extraction tower. The extraction with chlorphenol and chloracetic acid was made at a temperature of 76 F., using the modified solvent in the proportion of 1.8 parts of solvent to 1 part of undiluted oil. The extraction with chlorphenol and ethylene chlorhydrin was made at '74 F., using a solvent ratio of two parts of modified solvent to one part of undilutedoilr The resulting extract and rafiinate phases were separately removed and the solvent recovered therefrom by distillation. The following tabulation affords a comparison of the tests on the resuiting raihnate in each case with the original oil.

Olfilorphenol, Ohilgnihenol, c oracetice y ene- Reslduum acid raifichlorhydrin nate raftinate Gravity, A. P. I 19. 9 26. 0 26.2 Saybolt Universal viscosity/2l0 F 120 79 80 Viscosity inclexn 69 104 Carbon residue, percent. 5. 6 l. 75 1. 5 Color Black Lt. green Lt. green Percent yield 66. 2 66. 0

It will be observed that in both instances a rela. tively high yield of rafiinate oil, namely around 66 was obtained. The rafiinate in each case was light green in color and had a relatively low carbon content, namely 1.75 and 1.5% respectively, as compared with the carbon residue content of 5.6% in the case of the original oil. Both raffinates had a high viscosity index, of 95 and 104 respectively, as determined by the method of Dean and Davis.

The relatively low carbon residue content of the foregoing rafiinates obtained from a residual type of stock, indicates the advantage of the solvent mixture of this invention as a deasphaltizing solvent. The solvent mixture of our invention thus provides a. combined separating and deasphaltizing solvent, and such that the asphaltic bodies and the low viscosity index constituents may be removed simultaneously from the oil in a single treating operation, thus avoiding the necessity of subjecting the oil to individual operations in which these undesired constituents of the oil are removed separately.

The results obtained with the solvent mixture of our invention are comparable with and even superior to those obtained by the more usual type of operation in which the oil is deasphaltized in a preliminary or separate and distinct operation, and the asphalt free oil then subjected to separation With another solvent.

Reference has been specifically made in the above experiment todiluting the oil undergoing treatment With pentane. It is contemplated however that other suitable diluents may be employed, as for example propane or butane or mixtures of light hydrocarbons of this character such as in natural gasoline.

The temperatures, aswell as the solvent proportions, may differ considerably from those specified above, and may be varied'as desired in order to obtain the particular degree of solvent refining action desired. 7, V

cosity index constituents 'of Obviously many modifications and variations of the invention as hereinbeforeset forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim: 7

1. The method of solvent refining residual lubricating oil fractions containing constituents of difiering viscosity indices as well as dark-colored and residual carbon-forming bodies which comprises extracting the oil with a solvent mixture comprising orthoand para-chlorphenol in about equal proportion and chloracetic acid, the chloracetic acid constituting around 20% or more of the phenol mixture, forming an extract phase comprising low viscosity index constituents together with'drak-colored and residual carbonforming bodies dissolved in the solvent,.and a rafiinate phase containing relatively high viscosity index constituents of light color and of low residual carbon content, and separating the two phases.

2. The method of solvent refining residual lubricating oil fractions containing constituents of diifering viscosity indices as well as dark-colored and residual carbon-forming bodies which comprises extracting the oil with a solvent mixture comprising orthoand para-chlorphenol in about equal proportion and ethylene chlorhydrin saturated With hydrogen chloride gas, the ethylene chlorhydrin constituting around 20% or more of the phenol mixture, forming an extract phase comprising low viscosity index constituents together with dark-colored and residual carbonforming bodies dissolved in the solvent, and a rafiinate phase containing relatively high vislight color and of low residual carbon content, and separating the two phases. I

3. The method according to claim 1 in which the residual lubricating oil fraction undergoing treatment is diluted with a light petroleum frac tion.

4. The method according to claim 2 in which the residual lubricating oil fraction undergoing treatment is diluted with a light petroleum fraction.

5. In the manufacture of relatively lightcolored lubricating oil of low residual carbon content from a petroleum residue by extraction With a monochlorphenol mixture containing a suifi ciently large proportion of the orthoisomer such that the mixture exerts substantial solvent ac tion upon high as well as substantially complete solvent action upon low viscosity index constitu ents of the oil, the steps comprising extracting the residue with said chlorphenol mixture containing a high proportion of the ortho isomer in the presence of an auxiliary solvent comprising chloracetic acid crease the solvent action of the ortho upon the high viscosity index constituents oil without substantially reducing the solvent capacity of the solvent mixture for asphaltic constituents of the oil, forming an extract phase comprising low viscosity index constituents together with dark-colored and residual carbonforming bodies dissolved in the solvent, and a isomer of the 'raifinate phase containing high viscosity index .6 0 in an amount suificient to de- 7 tent from a petroleum residue by extraction with a monochlorphenol mixture containing a sufficiently large proportion of the ortho isomer such that the mixture exerts substantial solvent action upon high as well as substantially complete solvent action upon low viscosity index con- ,stituents of the oil, the steps comprising extracting the residue with said chlorphenol mixture containing a high proportion of the ortho isomer I substantially reducing the solvent capacity of the I solvent mixture for asphaltic constituents of the oil, forming an extract phase comprising low viscosity index constituents together with darkcolored and residual carbon-forming bodies dissolved in the solvent, and a raflinate phase containing high viscosity index constituents of light color and of low residual carbon content, and

- separating the two phases.

7. Inthe manufacture of relatively light colored lubricating oil of low, residual carbon content from a. petroleum residue by extraction with a monochlorphenol mixture containing a suilicient ly large proportion of the ortho isomer such that the mixture exerts substantial solvent action upon high as well as substantially complete solvent action upon low viscosity index constituents of the oil, the steps comprising extracting the residue with said chlorphenol mixture containing a high proportion of the ortho isomer in the presence of an auxiliary solvent selected from the group consisting of chloracetic acid and ethylene chlorhydrin saturated with hydrogen chloride, forming an extract phase comprising low viscosity index constituents together with dark-colored and residual carbon-forming bodies dissolved in the solvent and a raflinate phase containing high viscosity index constituents of light color and of low residual carbon content, and separating the two phases.

3. The method according to claim 7 in which the petroleum residue is extracted with the solvent mixture in the presence of a low-boiling petroleum hydrocarbon.

LOUIS A. CLARKE. EDWIN C. KNOWLES. 

